Nano-enabled Energy Conversion, Storage
and Thermal Management Systems (NEXT) Group
Director: Dr. Ronggui Yang, Assistant
Professor of Mechanical Engineering
Office Location: ECME 136,
Post-Doctor Offices: ECME 251A, ECME
251B
Student Offices and
Labs: ECME 165, ECME 219, ECME 1B80
Tel: 303-735-1003 (O), 303-735-1763 (Lab);
Fax: 303-492-3498
People Research Publications Facilities Open Positions News
Currently our research spans over developing
numerical/theoretical and experimental tools for understanding nanoscale
thermal transport, probing new transport phenomena in nanocomposites, hybrid
inorganic-organic crystals, and hybrid micro/nano-structures, and applying the
discoveries in fundamental sciences at micro/nano-scales to thermal management
and energy conversion/storage systems. To better reflect the expertise and the
research activities of our multi-disciplinary research team, we recently
re-named our “Nanoscale and Ultrafast Thermal Sciences and Applications (NUTS)”
group built in January 2006 to “Nano-enabled Energy Conversion, Storage, and
Thermal Management systems (NEXT)” group.
A)
SELECTED RESEARCH AREAS:
1.
Modeling and Simulation of Nanoscale Thermal and Thermoelectric Transport:
As the size of structures approaches the
nanoscale, the conventional Fourier law of heat conduction does not remain
applicable. We are interested in understanding how heat transfer in
nanostructures differs from that in macrostructures and how to model and
predict the heat transfer in nanostructures. We have developed the
deterministic (discrete ordinate method and finite volume method) and
stochastic (
2. Soft X-ray for Probing Nanoscale and Ultrafast Thermal Transport:
Femtosecond laser
is a unique tool to study a number of ultrafast relaxation processes and nanoscale
phenomena. We have constructed a femtosecond two color (blue &
near-infrared) pump-probe system with 8 ns delay time with the aim to extract
the phonon relaxation time and phonon reflectivity at interfaces which are
essential parameter inputs for nanoscale thermal transport
modeling/simulations. This experiment system is now on daily operation for
studying electron energy relaxation, phonon energy relaxation, and
electron-phonon coupling in bulk and nanostructured materials. Collaborating
with ourphysics colleagues Professor Margaret Murnane
and Professor Henry Kapteyn of JILA/physics at
CU-Boulder, we have been constructing a pump-probe system using the table-top
femtosecond soft X-ray beams. The soft X-ray offers many advantages over
visible or infrared light due to its short wavelength (selective wavelength of
2-30nm). We have recently used the change in diffraction from
micro/nanostructured gratings to directly observe the transition between
diffusive and ballistic heat transport. The initial report of this
groundbreaking work in CLEO conference has attracted a lot of interest and was
highlighted as one of the 5 CLEO Technical News Summaries (May 2008) and later
was highlighted again as one of the 4 Physics Update items in the July 2008
issue of Physics Today, the membership magazine of the 120,000-member American
Institute of Physics. p.17 (July 2008). Very recently,
a journal paper reporting this experimental observation has been accepted by
Nature Materials.
The experimental
system we developed enables us to further understand nanoscale and ultrafast
thermal transport fundamentals. Currently we focus on demonstrating the
possibility of using soft X-ray to image thermal transport with nanoscale
spatial and picosecond temporal resolutions simultaneously. The success of such
an implementation will enable us to watch how thermal energy is dissipated in
the drain side of nanoscale transistors, how the heat is propagated through an
interface of dissimilar materials, how the heat is generated and transported
surrounding nanoparticles in a variety of
environment.
3. Micro/Nano-Enabled Thermal Management
The scaling down of feature sizes in
microelectronic devices leads to an increase in heat dissipation per unit
volume that consequently may affect device performance and reliability. A very
similar concern arises in the design of high power semiconductor lasers in
which heat generation can become extreme. Further, the energy conversion
technologies also rely on efficient thermal management. For example, the
external thermal management solutions boost the efficiencies of thermo-photovoltaics and solar cells by increasing the heat
removal capability. Nanotechnology not only creates hurdles but also solutions
for thermal management. Working with our colleagues Professor YC Lee, Professor
Victor Bright and Professor Steven George of CU-Boulder and Professor Chen Li
and Professor G.P. Peterson, we conceptualized the possibility to build
flexible thermal ground planes that have 100 times better thermal conductivity
than diamond, the best natural thermal conducting material, by utilizing phase
change heat transfer in hybrid micro/nano- wicking structures encased in
millimeter-thick polymer chamber. Such an innovation will enable a new
generation of high-performance, integrated microelectronic, power conversion,
photonic or microwave systems operating at high power density without
constraints resulting from complex thermal management solutions. The key to our
innovation is manufacturable micro/nanotechnologies
for low-cost applications and the in-depth understanding of phase change heat
transfer. We will significantly further the understanding of how
micro/nano-structures could improve phase change heat transfer by this study.
4.
Nano-Enabled Energy Conversion and Storage:
One of our most successful applications in tailoring transport properties is nano-thermoelectrics, for which we use nanotechnologies to engineer structures to have thermal conductivity lower than alloys while maintaining electron power factor (electrical conductivity times the square of thermoelectric Seebeck coefficient), which is not achievable in bulk materials. Collaborating with Professor Gang Chen and Professor Mildred Dresselhaus who are pioneers in nanostructured thermoelectrics, we laid out the theoretical foundation for proposing nanocomposites as high efficient thermoelectric materials during my Ph.D study at MIT. Our nanocomposite work brought in a paradigm-shift to thermoelectric research from the proof-of-concept demonstration to a potential commercial product since nanocomposites can be cost-effectively fabricated to realize nano-enabled efficiency enhancement. Our current work on thermoelectrics include: 1) modeling and characterization of various thermoelectric nanostructures, 2) developing atomic-layer deposition-enabled low-cost thermoelectric nanocomposites that are low-cost but could potentially have similar efficiency as superlattices, 3). developing integrated thermoelectric systems for solar-electricity, waste heat recovery and thermal management. In addition, we are also collaborating with Professor Se-Hee Lee on core-shell silicon nanowires for lithium ion battery electrode applications. An interesting project we are pursuing is the on-chip integration of silicon-nanowire array-enabled photovoltaic and lithium ion batteries which could provide potentially 24-hour uninterrupted solar power-supply.
B). RESEARCH AWARDS (to PI Professor Ronggui Yang):
2009-2014 National Science Foundation (NSF) CAREER Award (the National Science Foundation's most prestigious awards in support of junior faculty who exemplify the role of teacher-scholars through outstanding research, excellent education and the integration of education and research within the context of the mission of their organizations.)
2009 Selected as one of the <100 Invited
Participants, the US
National Academy of Engineering's (NAE) 15th U.S. Frontiers of
Engineering Symposium.
2009 Biography featured as a technology developer with outstanding potential that could reverse the decline in the book “The Decline of American Technology” by Dr. Lynn G. Gref, to be published in Spring 2010.
2008 Technology Review’s TR35 Award (one of the 35 young scientists and technologists in world who are under the age of 35, but their work--spanning medicine, computing, communications, electronics, nanotechnology, energy, and more--is changing our world.)
2008 DARPA/MTO Young Faculty Award (one of the 39 rising stars in university microsystems research)
2008-2011 Sanders Faculty Fellow,
2008 Outstanding Research Award, Department of Mechanical Engineering, CU-Boulder
2008 Nominated for IEEE/ACM William J. McCalla ICCAD 2008 Best Paper Award by the conference organizers of the 2008 International Conference on Computer-Aided Design (ICCAD).
2005 Best Paper Award – Research, InterPACK 2005 (the ASME/Pacific Rim Technical Conference and Exhibition on Integration and Packaging of MEMS, NEMS, and Electronic Systems), 1 out of 500+ papers.
2005 Goldsmid Award for Excellence in Research in Thermoelectrics, International Thermoelectrics Society.
2004 NASA Certificate of Recognition for a Technical Innovation (Space Act Tech Brief Award), NASA Inventions and Contributions Board.
2003 Elected full member of Sigma Xi, the Scientific Research Society.
C) RESEARCH
FUNDING
1. CAREER: An integrated research and education program on nanoscale thermal transport: developing a high spatiotemporal resolution photo-thermal microscope, National Science Foundation, PI: Ronggui Yang, $400K + $60K (university matching), 02/01/2009-01/31/2014.
2. Novel
Silicon/NixSn1-x Core-Shell Nanowires for
Superior High Capacity and Long Lifetime Lithium-Ion Batteries, PI: Ronggui
Yang, Co-PIs: Se-Hee Lee and Wei Wang,
3. A micro-scale hybrid wick heat pipe cooling system for high concentration photovoltaic cell, University of Colorado Technology Transfer Office Energy Initiative Proof of Concept Grant, PI: Chen Li, Co-PIs: Victor M. Bright, Ronggui Yang, Y.C. Lee, Total: $50K, Yang: $0, 04/01/2009-03/31/2010.
4.
Modeling and experiments in the nucleate boiling
regime in the context of power electronics cooling, National Renewable Energy Lab, PI: Ronggui Yang, $175K, 10/01/2008-09/30/2011.
5. Surface Plasmon Enabled High Efficiency Thermoelectric Devices, DARPA MTO Young Faculty Award, PI: Ronggui Yang, $150K, 06/01/2008-11/30/2009.
6. A Design tool for nanostructures with tunable thermal properties, AFOSR (BAA 2007-08 Discovery Challenge Thrusts), PI: Ronggui Yang, Co-PIs: Kurt Maute and Martin Dunn, $600K, 03/01/2008-12/31/2010.
7. Flexible thermal ground plane with micro/nano wicking structures, DARPA (BAA 07-36 Thermal Ground Plane), PI: Y.C. Lee, Co-PI: Ronggui Yang, Chen Li, Victor Bright, G.P. “Bud” Peterson, and Suraj Rawal, $4.0M, 04/01/2008-12/30/2011.
8.
Nanowire-based metamaterials for miniaturized antennas, DARPA iMINT
Center Seed Grant, PI: Won park,
Co-PIs: Ronggui Yang, Y.C. Lee, and Pavel Kabos, T. Mitch Wallis, Jim Booth, Total: $50K, Yang; $0,
04/01/2008-03/31/2009. completed
9.
MRI-Consortium: Acquisition of a Supercomputer by
the Front Range Computing Consortium, National Science Foundation (Award #0821794), one of ~50 CU Faculty
Participants with PI Henry Tufo, $2.8M, Yang: $0, 8/1/2008 -
7/31/2012.
10. Nanocomposite thermoelectric materials development and
characterization, Lockheed Martin Corporation, PI: Ronggui Yang, $50K,
10/25/2007-11/15/2008. completed
11. A
design-centered approach to
nano-engineering, National Science Foundation, PI: Kurt Maute, Co-PIs: Martin
Dunn and Ronggui Yang, $329,957, 09/01/2007-08/31/2010, 0.25 summer month.
12. Understand
the building with your eyes: building and environment science and technology visualization Lab. CU-Engineering
Excellence Fund, co-PI with
John Zhai. $26,695, 05/01/2007-04/01/2008. completed
13. Unrestricted
gift fund, $6,000, 10/15/2007 ~.
14. Energy
harvesting and storage systems and their integration into AF aero vehicles, Air
Force Office of Scientific Research - Multidisciplinary University Research
Initiative (AFOSR-MURI); PI: Minoru Taya, Co-PI with
8 other co-PIs, total: $6M, CU: $1.50M, Yang: $500K, 05/01/2006-04/30/2011.
15. Measurement
of thermal transport in nanostructures
using EUV pump-probe systems, National
Science Foundation; PI: Ronggui Yang (Funded through the
16. Constructing a femtosecond nanometer
resolution photo-thermal imaging system using extreme ultraviolet (EUV) to
study nanoscale thermal transport, National Science Foundation; PI: Ronggui
Yang, Co-PI: Margaret Murnane, $94,919, 09/01/2006-08/31/2007. completed
17. Photonic crystal fiber based micro capillary
pumped loops, CU Technology Transfer Office Proof of Concept Grant (POCg); PI: Ronggui Yang, $12,500, 12/01/2006-05/31/2007. completed
18. Photonic crystal fiber based micro heat pipe
arrays and capillary pumped loops, CU Engineering Dean’s Seed Fund for Novel
Ideas; PI: Ronggui Yang, Co-PIs: Y.C. Lee and Victor M. Bright, $10,000,
06/10/2006-12/31/2006. completed
19. Unrestricted
gift fund, $15,000, 08/15/2006 ~.
20.